DD291490A5

DD291490A5 - PRESS FORM FOR THE MANUFACTURE OF CERAMIC MATRICES

Info

Publication number: DD291490A5
Application number: DD33719690A
Authority: DD
Inventors: Klaus Lietzmann; Lothar Michalowsky; Katja Kramer; Andreas Rendtel; Rainer Sack; Michael Teichgraeber
Original assignee: Freiberg Bergakademie
Priority date: 1990-01-19
Filing date: 1990-01-19
Publication date: 1991-07-04

Abstract

Die Erfindung betrifft das Gebiet der Metallformung und ist zur Herstellung von Formgebungswerkzeugen auf der Basis von Matrizen aus Keramik fuer die Formgebung von Metallen durch Ziehen, Stoszen, Druecken oder Extrudieren anwendbar. Erfindungsgemaesz ist in einem Hochdruckgefaesz mit Hochdruckmedium eine Preszform angeordnet. Die Preszform besitzt eine zylinderfoermige, mit Bohrungen versehene halbschalenfoermige Metallhuelse, an deren Innenseite sich eine schlauchfoermige Gummihuelse befindet. Die Preszform weist stirnseitige Verschluesse mit Halterungen fuer den Zentralstift und einen konischen Einsatz, die wiederum in der Symmetrieachse ineinander um den Verdichtungsanteil beim kaltisostatischen Pressen verschiebbar sind, auf. Der Zentralstift und der konische Einsatz sind in ihrer Gestalt der jeweiligen Querschnittsform der OEffnung der spaeteren Matrize angepaszt. Der Innenraum der Preszform kann mit pulverfoermigem keramischen Werkstoff gefuellt werden, wobei dieser vorher als feinkoerniges Granulat aufbereitet wird.{Preszform; Keramik; Matrizen; Formgebung; Metalle; Ziehen; Werkstoff, keramisch; Hochdruckmedium; Granulat; Pressen, kaltisostatisch}This invention relates to the field of metal forming and is applicable to the production of ceramic die-based forming tools for metal forming by drawing, stamping, pressing or extruding. According to the invention, a press mold is arranged in a high pressure vessel with high pressure medium. The Preszform has a cylindrical, provided with holes Halbschalenfoermige metal sleeve, on the inside is a hose-shaped rubber sleeve. The press mold has end caps with holders for the central pin and a conical insert, which in turn can be displaced in the axis of symmetry into one another by the compression ratio during cold isostatic pressing. The central pin and the conical insert are adapted in shape to the respective cross-sectional shape of the opening of the later die. The interior of the mold can be filled with pulverulent ceramic material, whereby this is prepared beforehand as feinkoerniges granules {Preszform; ceramics; matrices; design; metals; Pull; Material, ceramic; High pressure medium; Granules; Pressing, cold isostatic}

Description

Die Preßform gestattet, daß mit der Formgebung der Matrize gleichzeitig die notwendige Form des Innenraumes exakt ausgebildet wird und so z. B. die Form des Einziehkonus, der Umformzone einschließlich Gloit- und Auslaufkonus erhalten werden. Dabei werden durch dia Ausbildung der erfindungsgemäßen Preßform die Probleme bei der Schrumpfung des keramischen Körpers gelöst und somit macht sich kein aufwendiges mechanisches Einarbeiten der Öffnungen in den Kern erforderlich.The mold allows that the shape of the die at the same time the necessary shape of the interior is formed exactly and z. B. the shape of the Einziehkonus, the forming zone including Gloit and outlet cone are obtained. In this case, by dia formation of the press mold according to the invention, the problems in the shrinkage of the ceramic body are solved and thus makes no complicated mechanical incorporation of the openings in the core required.

Ausführungsbelsplel The invention will be explained in more detail in the following embodiment. In Fig. 1, the press mold according to the invention is shown schematically in an expedient embodiment. The mold has a cylindrical, provided with 12 evenly spaced holes shell-shaped Metal sleeve 1 made of steel. The inside wall side are a tubular rubber sleeve 2 and the front side closures with Mounts 5 arranged. The brackets are on each of a rubber disc 6, a pressure plate 7 undoiner Pressure nut 9 existing seals sealed. In the holders 5 are a central pin 4 and a conical insert 3, the

in ihrer Form jeweils der Querschnittsform der öffnung der späteren Matrize entsprechen, in der Symmetrieachsegegeneinander verschiebbar angeordnet. Der Innenraum der Preßform ist vor dem Verdichten mit dem pulverförmiger!correspond in shape each of the cross-sectional shape of the opening of the later die, arranged displaceable in the axis of symmetry against each other. The interior of the mold is before compacting with the powdered!

keramischen Werkstoff 11 gefüllt.filled ceramic material 11.

The mold is before the cold isostatic pressing in the high pressure liquid, in the present example glycerol, the

hydraulischen Presse eingebracht.introduced hydraulic press.

In the embodiment, ceramic powder based on SiC with a specific surface of> 15 mVg and a D _M value <0.7 .mu.l additives and with the addition of stabilizer mixed and freeze-dried by liquid N ₂ at -45 ° C.

und anschließend zu einem foinkörigen rieselfähigen Granulat verarbeitet. Das Granulat wird in die erfindungsgemäße Preßformeingefüllt und bei RT und einem Druck von 150 MPa auf eine Dichte von 75% der theoretischen Dichte gepreßt. Diese Vorformwird aus der Preßform entnommen und bei einer Temperatur von 150°C einer thermischen Nachbehandlung unterzogen.and then processed to a foaming granular free flowing granules. The granules are filled in the mold according to the invention and pressed at RT and a pressure of 150 MPa to a density of 75% of the theoretical density. This preform is removed from the mold and subjected to a thermal aftertreatment at a temperature of 150 ° C.

Subsequently, at a temperature of 2100 ⁰ C for about 1 hour in an argon atmosphere to a density> 97% of

theoretischen Dichte gesintert. Der gesinterte Rohling wird mit Diamantpaste unterschiedlicher Körnung geschliffen undanschließend auf Fertigmaß poliert.sintered theoretical density. The sintered blank is ground with diamond paste of different grain size and then polished to finished size.

Claims

1. mold for the production of matrices made of ceramic by cold isostatic pressing ceramic powder, characterized in that in a high-pressure vessel with a cylindrical, provided with bores metal sleeve (1) and the inside wall a tubular rubber sleeve (2), the end-side closures with holders (5 ), each receiving one of the cross-sectional shape of the opening of the later die adapted central pin (4) and a conical insert (3) and are surrounded by the pulverförmlgen ceramic material (11) are arranged.

2. Press mold according to claim 1, characterized in that the conical insert (3) and the central pin (4) in the axis of symmetry are arranged one inside the other by the compression ratio of the powder during cold isostatic pressing.

For this 1 page drawing

Field of application of the invention

The invention relates to the field of motor forming and is applicable to the production of mold tools based on ceramic dies for the shaping of metals by drawing, pushing, pressing or extruding.

Characteristic of the known state of the art

The use of dies is known for forming metallic materials by drawing, pressing, pushing or extruding. To ensure an effective Verfahransökonomie and, inter alia, for reasons of mechanical strength required to absorb the forming force at room temperature and at higher temperatures, to ensure a low Matrizenwerkstoffverschleißes and good surface quality of Umformgutes these matrices depending on Umformart example, hot-work, hard metals, hard composites, natural or artificial diamond, polycrystalline boron nitride and made of ceramic materials. In particular, the possibility of ensuring a high service life of the matrices at room temperature has led to the increased use and production of matrices from ketömischen materials. Thus, according to the US-PS 4038858 a wire drawing tool made of ceramic material is known. Also, according to US-PS 4270380 and SU-PS 286559 solutions for the use of ceramic materials for the production of Umfoimwerkzeugen have been proposed. All these solutions are based on the use of Al ₂ O _3, SiC, Si ₃ N ₄ and compound solutions involving a constructive solution 7um applying external pressure stresses on the forming of ceramic materials to ^d: offset e sensitivity of such materials to tensile stresses. Since such tensile stresses arise in the die due to the compressive stresses in the forming zone, solutions for reducing these stresses are offered. The problem is the incorporation of the appropriate, necessary for forming openings (inlet cone, sliding zone, outlet cone) in the hard, wear-resistant core of ceramic. A laborious and time-consuming machining by electric and spark erosion, drilling, grinding and polishing is required to adjust the profile shapes necessary for pulling. These stages make it difficult to use ceramic materials, especially from an economic point of view.

Object of the invention

The aim of the invention is to require less labor and time in the production of dies made of ceramic materials with special dimensions for the shaping of metallic materials for the production of the openings in the core.

Explanation of the essence of the invention

The invention has the technical object zugi unde to develop a mold with which matrices made of ceramic materials for the shaping of metallic materials without complicated mechanical processing of cores made of hard, wear-resistant ceramic can be produced.

According to the invention the object is achieved in that a press mold is arranged in a high pressure vessel with high pressure medium. The mold has a cylindrical, provided with bores half-shell-shaped metal sleeve, on the inside of which is a tubular rubber sleeve. The mold has frontal closures with brackets for the central pin and a conical insert, which in turn are slidable in the symmetry axis to each other by the compression ratio during cold isostatic pressing, on. The central pin and the conical insert are adapted in shape to the respective cross-sectional shape of the opening of the later die. The interior of the mold can be filled with powdered ceramic material, which is previously prepared as a fine-grained granules. Subsequently, according to the invention, a cold isostatic pressing takes place at room temperature under a pressure of> 100 MPa. After a thermal aftertreatment and the sintering process, the resulting matrix is subjected to mechanical finishing by grinding and polishing.